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基于DNA双链电荷转移原理,利用胸腺嘧啶(thymine)与Hg~(2+)的特异性识别和计时电量法构建了一种高灵敏检测水溶液中Hg~(2+)的电化学生物传感器。该传感器将含有1个T-T碱基错配对的DNA互补双链通过Au-S键自组装在金电极表面,运用计时电量法在含有亚甲基蓝的铁氰化钾溶液中进行测定。T-T错配阻断了DNA双链内部电荷转移,而Hg~(2+)通过T-Hg~(2+)-T配位作用与双链DNA特异性结合并形成DNA双链内部电荷转移通路,引起电极表面计时电量的变化。计时电量测定结果显示:在亚甲基蓝的还原峰电位(-380m V)附近,计时电量随着溶液中的Hg~(2+)浓度的增大而增加,Hg~(2+)浓度在1.0 nmol/L~104nmol/L范围内,计时电量的变化量与Hg~(2+)浓度的对数呈良好的线性关系,线性相关系数(R2)为0.997,检测限为0.5 nmol/L(S/N=3)。干扰实验表明,该传感器对Hg~(2+)具有良好的特异性和选择性。
Based on the principle of DNA double - stranded charge transfer, a sensitive electrochemical biosensor for the determination of Hg 2+ in aqueous solution was constructed using the specific recognition of thymine and Hg 2+ and the chronocoulometry method. The sensor self-assembled on the surface of the gold electrode by Au-S bond with a DNA complementary double strand containing one T-T base mismatch pair and measured in a potassium ferricyanide solution containing methylene blue by a chronoamperometry. TT mismatch blocks DNA double-strand internal charge transfer whereas Hg 2+ specifically binds to double-stranded DNA through the T-Hg ~ (2 +) - T coordination and forms a DNA double-strand internal charge transfer pathway , Causing changes in the electrode surface timing power. The results of chronocoulometry showed that the chronoamperometry increased with increasing concentration of Hg 2+ in the solution of methylene blue at -380 mV. The concentration of Hg 2+ was about 1.0 nmol / The linear correlation coefficient (R2) was 0.997 with the detection limit of 0.5 nmol / L (S / N = 3). Interference experiments show that the sensor has good specificity and selectivity for Hg 2+.